I've done it several times with a certified check. Put it in the mail then asked the seller to contact me when they received and deposited it. The sellers have told me it would take X days to clear. That is fine as chances are if you call a hauler today, they won't be able to pick it up for several weeks. Yep, you want the car for sure but there is a process and it takes time. Doesn't sound like the buyer is trying to rush anything so that is great. I had have always had more issues with the shippers than the sellers.